Combining ray-trace and diffraction analysis: A design example

An example is presented of using a combined ray trace and diffraction modeling code to simulate effects of objective-lens tilt in an optical data storage device. In some cases, neither ray-trace analysis nor diffraction analysis can give an adequate description of an optical system. The designer that is faced with the problem of analyzing such a system is forced to use a ray-trace program to determine aberrations in the exit pupil and then introduce aberration coefficients into a diffraction model that simulate the propagation. This approach was found rather awkward, especially if complicated aberrations are present. Our approach is to integrate a diffraction analysis and a ray-trace description of an optical path into one program. Our design is taken from a data storage application, where we must analyze the effects of objective-lens tilt

Measurement of laser spot quality

Several ways of measuring spot quality are compared. We examine in detail various figures of merit such as full width at half maximum (FWHM), full width at 1/(e exp 2) maximum, Strehl ratio, and encircled energy. Our application is optical data storage, but results can be applied to other areas like space communications and high energy lasers. We found that the optimum figure of merit in many cases is Strehl ratio

Laser beam modeling in optical storage systems

A computer model has been developed that simulates light propagating through an optical data storage system. A model of a laser beam that originates at a laser diode, propagates through an optical system, interacts with a optical disk, reflects back from the optical disk into the system, and propagates to data and servo detectors is discussed

Differential spot-size focus servo

We describe performance of a differential spot-size (wax-wane) focus servo. Crosstalk from the tracks are analyzed in the single detector and differential focus circuits. Magnitude of the crosstalk is reduced by a factor of three in the differential circuit. A false focus-error signal (FES) is present when the spot crosses sector marks at an angle

The research of the pulsed electron beam effect on polylactic acid scaffolds

The effect of nanosecond pulsed electron beam irradiation on properties of polylactic acid (PLLA)scaffolds was investigated. Modification of scaffolds was performed in electron beam accelerator with absorbeddose from 30 to200 kGy. Properties of the scaffolds were examined by means of XRD analysis and scanningelectron microscopy. It was shown that pulsed electron beam exposure leads to the recrystallization and changesin surface morphology

GERM3220-01.Intermediate German II.Sp17.Treptau,Bastian

Goals: To review all topics of German grammar and to enhance all the skills required for proficiency. Content: Readings in German, exercises in grammar and vocabulary building; equal emphasis on speaking, understanding the spoken language, writing, and reading. Taught: Annually. Recommended prerequisite: GERM 3210 or equivalent. Credits:

GERM3980-01.Special Topics: Adv German.Sp17.Treptau,Bastian

Goals: To enable students to speak and write more proficiently and more idiomatically leading toward mastery of fine points of German structure and style. Students learn to express convincingly their own ideas in German in response to specific works of art ranging from essays and short stories to feature films. Students will also gain insight into a range of significant contemporary works of literature and film and acquire the means to analyze and interpret these works in German. Content: Weight is given to both conversation and composition, with an emphasis on conversation and oral examination, reflection, and presentation. Written and oral exercises focus on discursive patterns and the most frequent sources of lexical and syntactical errors. Conversations and written work are based on contemporary works of literature (specifically essays, short stories, and pop literature) as well as a wide range of films accompanied by the theoretical foundation of how to interpret films in German

GERM3900-01.Adv German ConversatnCompositn.F16.Treptau,Bastian

Goals: To enable students to speak and write more proficiently and more idiomatically leading toward mastery of fine points of German structure and style. Students learn to express convincingly their own ideas in German. Content: Equal weight is given to conversation and composition. Written and oral exercises focus on discursive patterns and the most frequent sources of lexical and syntactical errors. Conversations and essays are based on all genres and films as well as on current German cultural issues. Taught: Annually Prerequisite: GERM 3220 Credits: